Developing and testing an optimal search strategy for identifying studies of prognosis

Irvin E, Hayden J

Background: In recent years there has been a rapid increase in the use of systematic review methods to synthesize the evidence on questions related to prognosis. However, the methods of prognostic systematic reviews are not well developed. An important part of a systematic review is the literature searching. There are several reasons for uncertainty in searching for prognosis studies: indexing of prognostic studies is inconsistent and it is not possible to apply the PICO (Population, Intervention, Comparison, Outcomes) method of searching. Work on developing effective strategies has begun. However, these approaches need to be tested, and our experience has indicated that perhaps these strategies may be further refined.

Objectives: In the context of a systematic review of prognostic factors for low back pain we will develop an adequately sensitive and specific search strategy for identifying prognostic studies.

Methods: A comprehensive literature search has been conducted based on the combined search strategies of the Cochrane Back Group and the sensitive search strategy for prognosis studies recommended by Altman1 for the following databases (all available years): MEDLINE, CINAHL and HealthStar. The search to May 2004 yielded 8823 distinct citations. A review of reference lists, handsearching of relevant journals and personal libraries, and a Science Citation Index search of relevant publications will supplement the search. Citation screening was done with two independent reviewers. Several steps of article screening occurred, including complete classification of studies by study purpose, population, and study design, to allow investigation. It was felt that while the electronic search conducted could confidently be described as sensitive, it lacked specificity. The authors will use this citation database as a gold standard in testing and improving upon the developed and published prognostic strategies.

Conclusions: By improving the existing prognostic search strategies the authors propose to make the challenge of finding such articles less problematic and more efficient.

References

1. Altman DG. Systematic reviews of evaluations of prognostic variables. BMJ 2001;323:224-8.